Water filters are typically disposed of after a single use; they are not typically cleaned and reused. The invention provides for the use of a peracetic acid disinfectant to clean particulate inorganic materials such as Calcium and Magnesium from hollow fibers and filters, particularly those formed from polysulfone, so that the filters may be reused. More specifically, the invention provides a method for soaking the filter material for 24 hours in a peracetic acid based solution, for example, a 1% Minncare.RTM. solution (available from Minntech Corporation, Minneapolis, Minn.), i.e., a 1% diluted solution of about 20% hydrogen peroxide, about 4% peracetic acid and water (peracetic acid), more specifically about 22% hydrogen peroxide, about 4.5% peracetic acid and water (peracetic acid). Both hollow fiber and pleated polysulfone filters may be cleaned with the peracetic acid solution in accordance with the method of the invention. Polysulfone filters cleaned in this manner have a reuse life of about 60%-80% of the original life of the filter. Other filters with different materials of construction may be soaked in the peracetic acid based solution in accordance with the method of the invention, but do not exhibit the dramatic reusability realized by soaking the polysulfone filter materials.
Heretofore Minncare.RTM. and other peracetic acid solutions have been used and marketed as sanitizing agents and are known and used to sanitize reverse osmosis membranes and water systems. To the inventors' knowledge, such solutions have not been known to be useful for nor used for cleaning particulate materials from filter membranes, thereby to clean the filters for reuse. Moreover, sanitizing only requires about 30 minutes of soaking and no significant cleaning occurs during the 30 minutes typically used for sanitizing.